Most often cough and cough in children is caused due to certain viral infections. Most often such infections are associated with allergic reactions which can be responsible for sneezing. Giving some antiallergic like cetirizine syrup for a few days should help in relieving the problem. I would not be separately concerned about the sore throat which is likely to be related. You can be patient and observe the child since such episodes usually last for 5-7 days irrespective of treatment. Give paracetamol in case the temperature rises. In case the child grows lethargic or starts wheezing, you would have to take the child to the emergency of a hospital without delay.